188
CASE STUDY OF ASSESSMENT AND CONTROL OF HIGHLY POTENT PHARMACEUTICAL COMPOUND.
B. Bidstrup, P. Tranchell, N. Rowe, Bristol-Myers Squibb Company, E. Syracuse, NY.
This presentation will focus on a case study of the small scale manufacture of a highly potent dermal sensitizer and the resulting assessment and controls that were required. The case study will include a brief overview of Bristol-Myers Squibb Company’s guidelines for the handling of potent pharmaceutical compounds, describe the exposure assessment activities completed, and conclude with a description of the immediate and long-term controls strategies employed.
In order to frame the case study, the presentation will introduce the company’s internal program for assigning compounds into exposure control bands, for developing internal occupational exposure limits, and discuss its design guidelines that recommend general control strategies for each exposure control band at the lab, pilot plant, and production scale.
The main portion of the presentation will provide an overview of the assessment and controls required to safely manufacture a potent R&D intermediate that is also a potent dermal sensitizer. The case study will review the qualitative and quantitative exposure assessment activities conducted to identify exposure sources, the process changes and controls required to limit exposures, and the control measures implemented to provide immediate protection as well as long-term permanent controls. Due to the potency and dermal sensitization characteristics of the compound, the control strategies included facility redesign, specially designed engineering controls, e.g., isolators, closed system sampling, and changes in the manufacturing process.
The presentation will also review a novel high volume pump system for monitoring potent compounds in operations where flammable liquids are also handled.
189
REDUCING WELDING EMISSIONS USING PULSED POWER INVERTER TECHNOLOGY VERSUS
CONVENTIONAL WELDING OPERATIONS.
K. Paulson, Naval Facilities Engineering Service Center, Port Hueneme, CA.
Welding operations are an intrinsic part of DOD equipment maintenance operations; hence, DOD is seeking to reduce welding emissions. Pulsed power (PP) inverter technology is reported to produce lower emissions when compared to conventional welding techniques. The study evaluates both mild steel and high tensile test samples at four DOD facilities (two Naval, one Marine, and one Army). Test samples are also evaluated for weld quality to determine if PP improves or equals the integrity of conventional welding.
Test plates, using actual material and fillers, simulated actual conditions and in most cases were tested nearby production operations. A fume ventilation system was erected to provide a steady (i.e., constant volume), relatively consistent source of fumes from each welding event. Particulate matter was withdrawn isokinetically from the ventilation system ductwork during welding operations (using a modified EPA Method 5 sampling train), and separated into nine particulate size ranges using a 9-stage cascade impactor in the fume sampling train. Each impactor stage was weighed to determine total particulate distribution. The contents of each stage were analyzed for 20 metals, including total chromium, hexavalent chromium, nickel, and manganese.
In addition to particulate/metal sampling, real-time continuous emissions monitoring is being conducted for NOx, CO, O3, and ultraviolet radiation (UV) by withdrawing a continuous gas stream from the ventilation system ductwork. UV readings are near the welder position.
Industrial hygiene engineering (area) samples were taken, using OSHA Methods 215 and 7300 for hexavalent chromium and total metal content, respectively. IH engineering samples were withdrawn continuously throughout each day of welding operations, both near the welding within two feet of the source and at a more remote location of 10 to 20 feet. Environmental and industrial hygiene findings will be reported for all four locations.
190
WOOD FLOOR REFINISHING—EXPOSURE AND CONTROLS.
M. Flanagan, University of Washington, Seattle, WA.
Wood floor refinishing is commonly recognized as a very dusty process with great potential for high solvent exposures. There is very little information available in the literature about wood dust or solvent levels describing this activity. This pilot project was an evaluation of activities for three contractors at five residential work sites, assessing exposure to total dust for the three tools used (sander, edger, and buffer) and for solvents used. Different local exhaust ventilation configurations were used including a trailer-mounted vacuum with ducting to the residence interior, and vacuum integrated as part of the tool. Finishing products used included water-based and low-solvent products, and two-part acid cured alcohol-based (Swedish finish) products.
The highest total dust levels occurred while edging, followed by buffing, then sanding (mean (SD) of 12.2 (21.0), 4.0 (5.3), and 3.7 (3.3) mg/m3, respectively). Local ventilation reduced dust considerably, with a reduction of 95% for edging, 85% for buffing, and 57% for sanding. Without ventilation, five or seven workers were overexposed to a full shift occupational exposure limit of 5.0 mg/m3. With ventilation, all workers were well below this limit.
The Swedish finish products produced much higher exposures than the low-solvent or water-based products. For both Swedish finish products, exposure to at least one chemical in the mixture was over the allowable short-term occupational exposure limit. For full shift solvent mixture exposures, the two Swedish finish products were at 140 and 60% of the mixture PEL after only 26 and 27 minutes of exposure, respectively. The low-solvent and water-based products were much lower at 2 and 1% of the full shift mixture PEL.
Wood dust levels can be very high during floor finishing and vacuum control makes an impressive reduction. The type of finishing products used has a big impact on the level of exposure to solvents.
191
THE THEORY AND PRACTICE OF USING ENCLOSURES FOR CONTROLLING NOISE.
G. Croteau, University of Washington, Seattle, WA.
The installation of an enclosure around a noise source can be a very effective method for reducing work related noise exposures and concomitant hearing loss. With the exception of eliminating, substituting, or potentially modifying the noise source itself, an enclosure is the most effective engineered noise control available. Although enclosures are relatively simple, achieving optimal noise reduction while having minimal impact on the production process requires some understanding of acoustics as well as the workplace. Designing an enclosure to be compatible with the manufacturing process can often be readily achieved if the workers involved in the operation and maintenance of the equipment are appointed the task of sizing the enclosure and determining the location of access ports. The amount of noise reduction achieved with an enclosure is largely dependent on both the sound transmission and absorption characteristics of the construction materials. The inside of the enclosure needs to be lined with a sound absorption material that is designed to absorb the dominant noise frequencies emanating from the noise source. Overall, transmission loss is a function of the enclosure’s mass and rigidity. Noise transmission and absorption are frequency dependent, necessitating the need to characterize the frequency distribution of the noise source. In addition to discussing the theory of how noise enclosures work, case studies of successful noise enclosure projects will be presented.
192
VERIFICATION OF RESPIRABLE SILICA CONTAINMENT OF LARGE PROCESS EQUIPMENT THROUGH
THE USE OF SF6 TRACER GAS.
F. Boelter, C. Simmons, D. Podraza, Boelter & Yates Inc., Park Ridge, IL.
Silica exposure related to escape from large process equipment in an environment such as a foundry is difficult if not impossible to determine by directly measuring respirable silica concentrations. A project was designed to quantify containment by use of a surrogate tracer gas utilizing recognized methodologies. Published literature discusses respirable silica behaving like a gas in the sense of following air current patterns. The ANSI/AIHA Z9.5-2003 Standard for Laboratory Ventilation and ANSI/ASHRAE 110-1995 Standard Method of Testing Performance of Laboratory Fume Hoods together establish a method and criteria for quantifying containment in “as-manufactured” and “as-installed” laboratory hoods. This paper details the scaling up process and application of the lab hood methodology in assessing large process equipment in a foundry setting. A number of issues needed to be addressed including: procedures to conduct airflow visualization tests of the ventilation system; determination of ventilation rates; selection of equipment and procedures for delivery of the compressed SF6 gas; determination of the gas injection location; development of the sampling strategy; and selection of direct reading equipment and analytical methods for air samples. The project concluded the methods can be utilized for the purpose of evaluating containment and that the equipment contributes no airborne respirable silica to the foundry.
193
SILICA ABATEMENT STRATEGIES IN CONSTRUCTION—IN DEPTH ANALYSIS OF OSHA CASE
FILES.
J. Capriotti, U.S. DOL/OSHA, Washington, DC; W. Long, Eastern Research Group (ERG), Arlington, VA; J. Delucca, U.S. DOL/OSHA, Dallas, TX.
Controlling crystalline silica exposures during construction jobs presents a challenge for safety and health professionals. An in-depth analysis of recent OSHA case files and other data shows that a variety of work practice and engineering controls can substantially reduce construction workers’ silica exposure levels most of the time. Examples from actual workplaces will show the value of conscientious dust control efforts. This presentation will highlight several innovative approaches that construction employers have taken to control employee exposures. For example, one OSHA case file showed how an employer built a plywood booth around a tabletop masonry saw and installed a large exhaust fan at the rear wall to pull dust away from the worker, who operated the saw through an opening in the front of the booth. After some modification of the booth interior, this control method reduced exposure to the worker by greater than one-half during the period evaluated. By adapting traditional wet methods and ventilation controls to meet their needs, these employers have decreased the severity and frequency of employee exposures (in some cases documented by pre- and post-abatement air sampling results). The purpose of this presentation is to reinforce the benefits of implementing a hierarchy of controls during construction work to show how taking simple, economical steps can reduce employee exposures to respirable dust and respirable crystalline silica.
194
MOISTURE AND MOLD BEHIND BRICK CLADDING.
S. Rucker, H.C. Nutting Company, Cincinnati, OH; D. Hart, Tremco Incorporated, Cincinnati, OH; S. Bostwick, Steven J. Bostwick, Architect, Cincinnati, OH.
The removal of brick cladding from structures has been recommended as a mold remediation technique. In some instances, the rationale for this recommendation has come from assessments that include wall check samples and visual documentation of construction defects. This remedial action is expensive and has come under legal challenge. Is this assessment technique appropriately matched for its intended purpose to identify mold inside wall systems? The problem is that this assessment strategy fails to identify specific areas of damage. The technique may overstate the problem, or miss areas of damage.
In the Midwest, the cost of removing brick exteriors as part of a mold remediation is between $15 and $20 per square foot. Approximately, the same cost is incurred to re-install the brick cladding. For a 2500 SF suburban home with a brick wrap façade, the total cost can exceed $100,000.
The results of nonculturable fungal wall samples are a useful indicator of fungal growth, but samples collected inside wall assemblies are often overloaded with construction dust and may overstate fungal contamination. Visual identification of masonry defects is useful in determining construction defects, but often defects are random with more fundamental defects enclosed within wall systems.
The options for confirmatory testing of hidden problems within wall assemblies are discussed. The application of techniques such as thermal imaging, hydrogen density testing, and electroconductivity are presented, including attributes and limitations.
Several case studies are presented that illustrate wall system removal, both warranted and unwarranted, with the intention of introducing industrial hygienists not familiar with these nondestructive test methods on how they may be used in mold assessments. In particular, these techniques are useful for establishing mold remediation protocols for moisture intrusion in wall assemblies.
195
EVALUATION OF POINT AND LINE VERSIONS OF GAUSSIAN MODELS FOR AN OUTDOOR
DUST-PRODUCING INDUSTRIAL PROCESS.
J. Park, J. Rock, Texas A&M University, College Station, TX.
Gaussian-based plume dispersion models are currently used and run by federal agencies as well as academic and private sector businesses. Three models were tested and compared against data collected from an outdoor dust-producing industrial process. A line source model (LSM) was compared with a point source model (PSM) and a box model (BM) because the dust emission point moved along a line, acting as a continuous moving point source. The methods of estimating atmospheric dispersion have undergone considerable revision on the basis of experimental measurements during the last couple of decades. Few reports have been published with a LSM. The data from this study were used as a basis to compare with predictions of a finite line source model, an infinite line source model, a PSM, and a BM. The horizontal and vertical dispersion coefficients (σy, σz) for all models in this study were estimated at orthogonal distances of 1, 2, and 3 m away using the two video cameras, one at about 1 m and the other at a 10 m height. In this study, a PSM prediction was adequate for the aerosol dispersion at the distances which were short compared with the length of the line source.
Posted May 30, 2005